Embodiments of the invention relate to methods and corresponding apparatus for broadcast service following for a vehicle. The apparatus is arranged in the vehicle. The embodiments also relate to a computer program and a computer program product for broadcast service following for a vehicle.
In addition to pure broadcast systems such as Digital Audio Broadcasting (DAB), Frequency Modulation Broadcasting (FM), Amplitude Modulation Broadcasting (AM) and Digital Radio Mondiale Broadcasting (DRM), radio services can also be provided by means of cellular network communications systems like a Long Term Evolution system (LIE system) according to the wireless communication standard 3GPP Long Term Evolution, by using either typical unicast (one-to-one) transmissions or broadcast (one-to-many) transmissions with Enhanced Multimedia Broadcast Multicast Services (eMBMS).
Service following is a term used to define maintenance of the same audio or video content the user is experiencing when switching between different frequencies and/or transmission systems. Switching between different frequencies and/or transmission systems may be necessary when moving across different service areas in a Multi-Frequency-Network (MFN) or to cope with varying reception conditions that occur when e.g. travelling by car or between buildings inside a city.
WO 99/14874 discloses a method for test receiving alternative frequencies without interrupting the reception of DAB frames from the current reception frequency in a DAB receiver. The receiver scans the alternative frequencies carrying the same service content during null symbol periods of a DAB frame. The method allows a coarse synchronization to the alternative DAB frequency in order to allow for a frequency switch without noticeable interruption. This system and method requires an existence of a DAB system and a sufficient DAB coverage carrying the alternative frequencies.
DE 10 2013 215 728 A1 discloses the selection of a radio transmission channel from a group of radio transmission channels, each corresponding to different transmission technologies and I or use different infrastructure components and is produced via a data connection between a mobile unit and a central unit. The mobile unit comprises at least two radio units each formed for a data transmission via one of two radio transmission channels. For the selection of the radio transmission channel from the group of radio communication channels data of at least one earlier transmission link, so-called historical data, of at least one of the radio transmission channels are used.
The objects of the invention include providing methods and corresponding apparatus for broadcast service following for a vehicle which contribute to an improved service following between broadcast transmission systems, in particular in case of vehicle reception, which contributes to an improved user experience.
This and other objects are achieved by a method and a corresponding apparatus for broadcast service following for a vehicle. The vehicle is configured to receive signals of a Digital Audio Broadcast, DAB, system and at least of one cellular network based broadcast system.
For an anticipated service following from a given DAB service to a corresponding cellular network based broadcast service, continuously or in given time intervals a signal quality and/or signal availability of the DAB service and/or the cellular network based broadcast service in a route section the vehicle is expected to reach in a given time span is estimated dependent on a provided data base information including data representative for geographical locations of coverage gaps of the DAB service and/or geographical locations of coverage gaps of the cellular network based broadcast service and/or transition zones of the DAB service and the cellular network based broadcast service. Additionally or alternatively the signal quality and/or signal availability of the DAB service and/or the cellular network based broadcast service in the route section the vehicle is expected to reach in the given time span is estimated dependent on a service information that is included in a received DAB signal. The service information comprises data representative for geographical locations of coverage gaps of the DAB service and/or geographical locations of coverage gaps of the cellular network based broadcast service and/or transition zones of the DAB service and the cellular network based broadcast service. A handover from the DAB service to the corresponding cellular network based broadcast service is performed dependent on the estimated signal quality and/or signal availability.
The complementary use of cellular networks, by means of cellular network based broadcast transmission technology, to cover the coverage gaps of DAB networks improves user experience by removing the service interruptions caused by the lack of DAB coverage. In particular, the assistance with service information, and/or the data base information simplifies the switching procedure, thus reducing latency, and enables a seamless user experience. Moreover, the required service information can be introduced in the DAB service signal without any modification of the current standard, thus being backwards compatible with legacy DAB networks and systems.
The service information may comprise DAB service coverage information. The service information may be included in DAB transmission frames. Thus, the service information is available at every point in the coverage area of DAB services, i.e. before the need of switching to the cellular network based broadcast system arises and even before reaching the coverage zone of the cellular network based broadcast service. Thus, the vehicle is able to arrange for a switching procedure beforehand, allowing for some anticipation in the service following.
The given time span for anticipating the service following may be configurable.
According to one embodiment of the first and second aspect, continuously or in given time intervals the signal quality and/or the signal availability of the DAB service and/or the cellular network based broadcast service in the route section the vehicle is expected to reach in the given time span is estimated dependent on provided measurement data of a current digital audio broadcast service signal respectively a current cellular network based broadcast service signal received by the vehicle. Advantageously this allows for incorporating additionally actual circumstances in a surrounding area of the vehicle into the decision of whether a handover is required or not.
According to a further embodiment of the first and second aspect, the cellular network based broadcast service comprises an Enhanced Multimedia Broadcast Multicast Service (eMBMS). The use of eMBMS allows for a higher degree of efficiency for the simultaneous distribution of live audio content to a large number of users compared to cellular unicast transmissions.
According to a further embodiment of the first and second aspect, the handover is performed dependent on a current geoposition of the vehicle and/or an expected route of the vehicle and/or a velocity of the vehicle. Using the information of the current geoposition of the vehicle and/or the expected route of the vehicle and/or the velocity of the vehicle, the handover can be started further in advance. This facilitates synchronization of the two systems. The current geo-position of the vehicle and/or the expected route of the vehicle and/or the velocity of the vehicle may be provided by a vehicle navigation system and/or other suitable vehicle sensors.
According to a further embodiment of the first and second aspect, in the event that the handover is performed, the cellular network based broadcast service, which corresponds to the DAB service, is determined dependent on a DAB service ID information carried within user service descriptors contained in a cellular network based broadcast service signal. This allows for switching easily from the DAB service to the corresponding cellular network based broadcast service.
According to a further embodiment of the first and second aspect, the service information included in the DAB signal of the received DAB service comprises or represents the user service descriptors of the cellular network based broadcast service. In this way the service information may be completely transparent to existing DAB receivers, but new DAB receivers may be able to read and treat the information carried in specific fields of the DAB transmission frame. The service information may be included in Frequency Information, FI, list fields. There exist some free Range and Modulation, R&M, values expected for future use. One of these free R&M values may be used to broadcast some useful information for the management of the switching procedure from the DAB service to the corresponding cellular network based broadcast service. According to a further embodiment of the first and second aspect, the user service descriptors of the cellular network based broadcast service corresponding to the respective DAB service are retrieved from a given data base. The data base may be accessed remotely and/or locally stored and updated to anticipate the switching procedure.
According to a further embodiment of the first and second aspect, the DAB service ID information of the respective DAB services is included in a Multimedia Broadcast Multicast Service User Service Description, such that a DAB service identifier, which identifies the DAB service, is included in the form of a Uniform Resource Name, URN, which is carried in the Enhanced Multimedia Broadcast Multicast Service system (eMBMS system), and all or nearly all user service bundles from the eMBMS system are collected and are searched iteratively for the DAB service identifier to find the corresponding cellular network based broadcast service. This, in the case that no further information from the data base or from the DAB signaling is available, allows for determining the user service descriptors of the corresponding cellular network based broadcast service.
According to a further embodiment of the first and second aspect, a synchronization between the DAB service and the cellular network based broadcast service is performed by buffering an audio content of the DAB service and/or the cellular network based broadcast service dependent on a given delay between the DAB service and the cellular network based broadcast service, wherein the delay is provided by the data base and/or the service information included in the received DAB signal. The synchronization allows for coping with existing delays between the DAB service and the cellular network based broadcast service and may ensure a seamless service following operation. For these purposes, for instance, a suitable receiver device may buffer the audio content by slowing down the reproduction or repeating the last seconds of the service. The cellular network based broadcast service delay with respect to the DAB may be made available in the data base and/or in the service information included in the received DAB signal.
According to a further embodiment of the first and second aspect, geopositions where the service following has been completed successfully are stored in the data base and/or another data base to be usable as the data base information.
This allows for complementing the list of service shadowing regions and, as the data base information is provided in a backend, may contribute to improved service following applications in alternative vehicles of, for example, an Original Equipment Manufacturer vehicle fleet.
Additionally, the vehicle may be configured to receive signals of a Digital Audio Broadcast, DAB, system and at least of one cellular network based broadcast system. For an anticipated service following from a given cellular network based broadcast service to a corresponding DAB service, continuously or in given time intervals a signal quality and/or signal availability of the corresponding DAB service and/or the cellular network based broadcast service in a route section the vehicle is expected to reach in a given time span is estimated dependent on a provided data base information including data representative for geographical locations of coverage gaps of the DAB service and/or geographical locations of coverage gaps of the cellular network based broadcast service and/or transition zones of the DAB service and the cellular network based broadcast service. A handover from the cellular network based broadcast service to the corresponding DAB service is performed dependent on the estimated signal quality and/or signal availability.
This allows for deciding at an early stage whether a handover to the DAB service is required or possible.
Additionally, the computer program may be designed to execute the method for broadcast service following for a vehicle according to the first or third aspect or to an advantageous embodiment of the methods by its execution on a data processing device.
Additionally, a computer program product may include executable program code, wherein the program code executes the method for broadcast service following for a vehicle according to the first or third aspect or to an advantageous embodiment of the methods by its execution on a data processing device.
The computer program product comprises, in particular, a means which is readable by the data processing device and on which the program code is stored.
Other objects, advantages and novel features of the embodiments of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.